Marine battery safety system and method

ABSTRACT

A marine battery pack including a battery enclosure having an exterior and an interior defining a cavity, wherein the battery enclosure is configured to protect against water ingress into the cavity. The marine battery pack further comprises a plurality of cell modules within the cavity, each including a plurality of battery cells, and at least one exterior sensor on the battery enclosure configured to sense at least one of an exterior temperature, an exterior pressure, and a presence of water on the exterior of the battery enclosure. A controller is configured to identify a water exposure event based on the at least one of the exterior temperature, the exterior pressure, and the presence of water on the exterior of the battery enclosure. A water exposure response is then generated.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application No. 63/172,895, filed Apr. 9, 2021, which is incorporated herein by reference in its entirety.

FIELD

The present disclosure generally relates to marine power storage systems configured for a marine environment, and more particularly to li-ion battery systems configured for installation in a marine environment, such as high voltage battery systems configured for installation on a marine vessel to power electric marine propulsion devices and/or other loads on a marine vessel.

BACKGROUND

Battery packs configured to power marine vessel loads, such as configured to power electric marine propulsion devices, store large amounts of energy. These battery packs, such as lithium-ion (li-ion) battery packs, have high energy densities and are configured to deliver energy at high currents and voltages. The energy is often stored in smaller storage elements, such as battery cells or groups of battery cells, housed and electrically connected together in series to generate a high voltage output. These battery packs generally have external housings, or enclosures, configured to protect the battery cells and prevent water ingress and also to safely contain the high voltage storage elements.

One major risk with li-ion battery packs, in particular, is thermal runaway. Li-ion battery thermal runaway occurs when a battery cell, or area within the cell, achieves elevated temperatures due to thermal failure, mechanical failure, internal short-circuiting, or an electrochemical abnormality of a cell or within the pack. At elevated temperatures, exothermic decomposition of the cell materials begins. Eventually, the self-heating rate of the cell is greater than the rate at which heat can be dissipated to the surroundings, and the cell temperature rises exponentially causing a chain reaction of exothermic decomposition of surrounding cells. When this occurs, the thermal and electrochemical energy stored in the battery is released to the surroundings.

The following patents and patent publications are hereby incorporated by reference in their entireties:

U.S. Pat. No. 9,630,686 discloses a pressure tolerant energy system. The pressure tolerant energy system may comprise a pressure tolerant cavity and an energy system enclosed in the pressure tolerant cavity configured to provide electrical power to the vessel. The energy system may include one or more battery cells and a pressure tolerant programmable management circuit. The pressure tolerant cavity may be filled with an electrically-inert liquid, such as mineral oil. In some embodiments, the electrically-inert liquid may be kept at a positive pressure relative to a pressure external to the pressure tolerant cavity. The energy system may further comprise a pressure venting system configured to maintain the pressure inside the pressure tolerant cavity within a range of pressures. The pressure tolerant cavity may be sealed to prevent water ingress.

U.S. Pat. No. 8,980,455 discloses a lithium-ion battery with a gas-releasing and explosion-proof safety valve, which comprises a casing and a battery core. The casing includes an opening that is sealed by a thermal cover, on which a safety valve is disposed. The safety valve comprises a safety cover and a pressure filter. A middle portion of the safety cover includes a through hole. The pressure filter is affixed to the middle portion of the safety cover and has numerous pores. The safety cover and thermal cover are hooked together.

U.S. Patent Application No. 2018/0013115 discloses a method for housing a battery used on a light-weight, motor powered watercraft includes the step of: providing a battery case having: a pod sized to house a marine battery, the pod having a cavity for the marine battery and an open top; a lid for at least water-resistant closure of the open top of the pod, the lid having a cavity and an open bottom, the lid is releasably attachable to the pod; and a floor releasably attached to the lid adjacent the open bottom, the floor adapted to hold controls for the light-weight, motor powered watercraft.

SUMMARY

This Summary is provided to introduce a selection of concepts that are further described hereinbelow in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

In one aspect of the present disclosure, a marine battery pack includes a battery enclosure having an exterior and an interior defining a cavity, wherein the battery enclosure is configured to protect against water ingress into the cavity. The marine battery pack further comprises a plurality of cell modules within the cavity, each including a plurality of battery cells, and at least one exterior sensor on the battery enclosure configured to sense at least one of an exterior temperature, an exterior pressure, and a presence of water on the exterior of the battery enclosure. A controller is configured to identify a water exposure event based on at least one of the exterior temperature, the exterior pressure, and the presence of water on the exterior of the battery enclosure. A water exposure response is then generated.

In one example, generation of the water exposure response includes generating a water exposure alert. For instance, the controller is configured to generate the water exposure alert by sending a command to a user interface system to generate a visual alert advising that the battery enclosure has been exposed to water.

In another example, the generation of the water exposure response includes adjusting at least one electrical connection in the marine battery pack to reduce a shock hazard. For instance, adjusting at least one electrical connection may include at least one of operating a high voltage contactor to disconnect the plurality of cell modules from an output terminal of the battery pack and/or operating at least one disconnect switch to disconnect the plurality of cell modules from one another to reduce voltage levels within the battery pack.

In another example, the battery pack includes a high voltage contactor inside the battery enclosure that controls connection of the plurality of cell modules to an output terminal of the battery pack, and wherein the water exposure response by the controller includes controlling the high voltage contactor to disconnect the plurality of cell modules from the output terminal of the battery pack.

In another example, the battery pack includes at least one disconnect switch that controls connection of the plurality of cell modules together in series, and wherein the water exposure response by the controller includes controlling the one or more of the disconnect switches to disconnect at least a portion of the plurality of cell modules from one another to reduce voltage levels within the battery pack.

In another example, the at least one exterior sensor includes a water sensor and the controller is configured to identify the water exposure event when the exterior water sensor senses the presence of water.

In another example, the at least one exterior sensor includes a pressure sensor configured to sense the pressure outside of the battery enclosure and the controller is configured to identify the water exposure event based on detection of at least one of a threshold pressure increase and a threshold pressure outside the battery enclosure.

In another example, the at least one exterior sensor includes a temperature sensor configured to sense the exterior temperature and the controller is configured to identify the water exposure event based on detection of at least a threshold change in temperature outside the battery enclosure.

In another example, the battery pack further includes an inert gas cartridge configured to release inert gas into the cavity, and wherein the generation of the water exposure response includes releasing the inert gas into the cavity to increase pressure in the cavity to prevent water ingress.

In another aspect of the present disclosure, a method of controlling a marine battery pack includes sensing, via at least one exterior sensor on a battery enclosure of the battery pack, at least one of an exterior temperature, an exterior pressure, and a presence of water on the exterior of the battery enclosure. A water exposure event is then detected with a controller based on at least one of the exterior temperature, the exterior pressure, and the presence of water. A water exposure response is then generated by the controller.

In one example, generating the water exposure response includes controlling a user interface system to generate a water exposure alert.

In another example, generating the water exposure response includes adjusting at least one electrical connection in the marine battery pack to reduce a shock hazard.

In another example, adjusting at least one electrical connection includes operating at least one of a high voltage contactor to disconnect a plurality of cell modules in the battery pack from an output terminal of the battery pack and at least one disconnect switch to disconnect the plurality of cell modules from one another to reduce voltage levels within the battery pack.

In another example, wherein the at least one exterior sensor includes at least one water sensor, and wherein detecting the water exposure event includes detecting the presence of water with the at least one water sensor. Optionally, detecting the water exposure event includes sensing the presence of water with the at least one water sensor for a predetermined time prior to generating the water exposure response.

In another example, the at least one exterior sensor includes a pressure sensor configured to sense the pressure outside of the battery enclosure, and wherein detecting the water exposure event includes detecting at least one of a threshold pressure increase and a threshold pressure outside the battery enclosure.

In another example, the at least one exterior sensor includes a temperature sensor configured to sense the exterior temperature outside of the battery enclosure, and wherein detecting the water exposure event includes detecting at least a threshold temperature change outside the battery enclosure.

In another example, generating the water exposure response includes releasing the inert gas into the cavity to increase pressure in the cavity to prevent water ingress.

In another aspect of the present disclosure, a method of controlling a marine battery pack includes sensing, via at least one exterior sensor on a battery enclosure of the battery pack, at least one of an exterior temperature, an exterior pressure, a presence of water on the exterior of the battery enclosure, and a battery orientation. A water exposure event is then detected with a controller based on at least one of the exterior temperature, exterior pressure, the presence of water, and the battery orientation. At least one electrical connected in the marine battery pack is then automatically controlled to reduce a shock hazard posed by the battery.

In one example, controlling the at least one electrical connection includes controlling a high voltage contactor with the controller to disconnect a plurality of cell modules in the battery pack from an output terminal of the battery pack.

In another example, controlling the at least one electrical connection includes controlling at least one disconnect switch with the controller to disconnect a plurality of cell modules in the battery pack from one another to reduce voltage levels within the battery pack.

In another example, the at least one exterior sensor includes at least one water sensor, and wherein detecting the water exposure event includes sensing the presence of water on the exterior of the battery enclosure.

In another example, detecting the water exposure event includes sensing the presence of water with the at least one water sensor for a predetermined time prior to adjusting the at least one electrical connection.

In another example, the at least one exterior sensor includes at least one of a pressure sensor and a temperature sensor, and wherein detecting the water exposure event includes detecting a threshold change in pressure or a threshold temperature outside the enclosure indicating at least partial immersion of the battery in water.

In another example, the at least one exterior sensor includes an orientation sensor, and wherein detecting the water exposure event includes detecting at least a threshold change in orientation of the battery pack.

Various other features, objects, and advantages of the invention will be made apparent from the following description taken together with the drawings.

BRIEF DESCRIPTION

The present disclosure is described with reference to the following Figures. The same numbers are used throughout the Figures to reference like features and like components.

FIG. 1 is a diagram illustrating an exemplary electric marine propulsion system having a power storage system comprising a marine battery pack according to an exemplary implementation of the present disclosure.

FIG. 2 is a schematic diagram of a marine battery pack according to an embodiment of the present disclosure.

FIG. 3 is an exploded view of a marine battery pack according to another embodiment of the present disclosure.

FIG. 4 is an exterior view of a marine battery pack according to another embodiment of the present disclosure.

FIGS. 5-7 are flow charts illustrating methods of controlling a marine battery pack according to embodiments of the present disclosure.

DETAILED DESCRIPTION

Vehicle electrification and the application of electric marine propulsion systems and lithium-ion (li-ion) battery technology for electrical energy storage poses a different set of hazards than traditional internal combustion engines and liquid fuel storage. Additional hazards are created in the marine environment when li-ion batteries having liquid organic electrolytes come in contact with water. The inventors have recognized that particular issues may arise relating to battery conditions on marine vessels and other marine-related electrical energy storage with li-ion cells boaters on open water may not be able to reach a safe location in event of a battery fire or other hazardous battery event. Moreover, having the vessel surrounded by water, which is a conductor, creates a hazard that needs to be accounted for when a catastrophic battery event occurs. Thus, the inventors have recognized a need for a marine battery system and monitoring methods that provide detection and mitigation of potential hazards of a battery-driven electric marine propulsion system.

Upon recognition of the foregoing problems, the inventors developed the disclosed marine battery safety system that can detect and address the hazards of a li-ion battery energy storage system with special consideration to the hazards posed by water exposure, submersion, and the potential for water ingress into the high voltage system. The disclosed system and method are configured to monitor the marine power storage system, such as a battery pack on a marine vessel or on a dock, via multiple sensors and detect a hazardous condition that warrants further action. The system may include various external and/or internal sensors and sensing analysis methods to detect a water exposure event where the battery pack has been exposed to and/or immersed in water, and/or to detect when an event has occurred that warrants immediate decommissioning of the battery.

Upon detection of external water exposure, for example, the system is configured to automatically trigger a sequence of safety systems to address and mitigate various hazardous circumstances, such as electric shock. For example, the system may be configured to disconnect the high voltage battery from the vessel load and/or open connections within the pack to break down the battery into several smaller units to reduce the overall voltage of the battery, thus reducing the shock hazard. Upon detection of internal water exposure or a catastrophic event, for example, the system is configured to automatically trigger a sequence of safety systems to address and mitigate various hazardous circumstances, including thermal propagation, and/or electrolysis gas buildup inside the battery pack enclosure. Under certain conditions where, for example, a battery fire is imminent, the system may be configured to automatically decommission the battery pack in a way that maximizes heat dissipation and minimizes the buildup of electrolysis gasses inside the battery pack.

FIG. 1 depicts an embodiment of an electric marine propulsion system 2 powered by a power storage system 16, such as a Li-ion battery pack. In the depicted embodiment, the electric marine propulsion system 2 includes an outboard marine drive 3 having an electric motor 4 housed therein, such as housed within the cowl 50 of the outboard marine drive. A person of ordinary skill in the art will understand in view of the present disclosure that the marine propulsion system 2 may include other types of electric marine propulsion devices, such as inboard drives, stern drives, jet drives, or the like. The exemplary electric marine drive 3 has an electric motor 4 configured to propel the marine vessel by rotating a propeller 10. The motor 4 may be, for example, a brushless electric motor, such as a brushless DC motor. In other embodiments, the electric motor may be a DC brushed motor, an AC brushless motor, a direct drive, a permanent magnet synchronous motor, an induction motor, or any other device that converts electric power to rotational motion. In certain embodiments, the electric motor 4 includes a rotor and a stator, as is well known in the relevant art.

The electric motor 4 is electrically connected to and powered by a power storage system 16. The power storage system 16 stores energy for powering the electric motor 4 and is rechargeable, such as by connection to shore power when the electric motor 4 is not in use. Various power storage systems 16 are known in the art and are suitable for powering an electric marine drive, such as various li-ion battery pack arrangements. In the depicted example, a bank or group of cell modules 18 is connected in series to provide a large voltage output. In one example, the high voltage power storage system 16 may include one or more li-ion battery packs of 250 V DC or more, such as 450 V DC, 550 V DC, or an even higher voltage pack such as 800 V DC.

The central controller 12, which in the depicted embodiment is a propulsion control module (PCM), communicates with the motor controller 14 via communication link 34, such as a CAN bus. The controller also receives input from and/or communicates with one or more user interface devices in a user interface system 35 via the communication link, which in some embodiments may be the same communication link as utilized for communication between the controllers 12, 14, 60 or may be a separate communication link. The user interface devices in the exemplary embodiment include a throttle lever 38 and a display 40. In various embodiments, the display 40 may be, for example, part of an onboard management system, such as the VesselView™ by Mercury Marine of Fond du Lac, Wis. The user interface system 35 may also include a steering wheel 36, which in some embodiments may also communicate with the controller 12 to effectuate steering control over the marine drive 3, which is well-known and typically referred to as steer-by-wire arrangements. In the depicted embodiment, the steering wheel 36 is a manual steer arrangement where the steering wheel 36 is connected to a steering actuator that steers the marine drive 3 by a steering cable 37.

Each electric motor 4 may be associated with a motor controller 14 configured to control power to the electric motor, such as to the stator winding thereof. The motor controller 14 is configured to control the function and output of the electric motor 4, such as controlling the torque outputted by the motor, the rotational speed of the motor 4, as well as the input current, voltage, and power supplied to and utilized by the motor 4. In one arrangement, the motor controller 14 controls the current delivered to the stator windings via the leads 15, which input electrical energy to the electric motor to induce and control rotation of the rotor. Sensors may be configured to sense the power, including the current and voltage, delivered to the motor 4. The motor controller 14 is configured to provide appropriate current and or voltage to meet the demand for controlling the motor 4. For example, a demand input may be received at the motor controller 14 from the central controller 12, such as based on an operator demand at a helm input device, such as the throttle lever 38.

Referring also to FIG. 2, power storage system 16 may be a Li-ion battery pack 16′ having an enclosure 64 defining a cavity 63. The power storage system 16 may further include a battery management system 60 configured to monitor and/or control aspects of the power storage system 16. For example, the battery management system 60 may receive inputs from one or more sensors within or on the power storage system 16, which may include a plurality of exterior sensors 23 and interior sensors 30. The exterior sensor(s) 23 may include an exterior water sensor 24 configured to sense the presence of water on the exterior of the enclosure 64. In one embodiment, the exterior water sensor 24 may be a capacitive water sensor. Alternatively, the exterior water sensor 24 may be a resistive sensor or a thermal sensor configured to detect contact with water. Alternatively or additionally, the exterior sensor(s) 23 may include one or more of an exterior temperature sensor 25 configured to sense an external temperature on the enclosure or a temperature of the environment surrounding the enclosure, and an exterior pressure sensor 26 configured to sense an external pressure on or around the exterior of the enclosure. In some examples, the enclosure may be configured with multiple water sensors 24, temperature sensors 25, and/or pressure sensors 26, such as positioned on multiple sides of the enclosure to provide information regarding all sides of the enclosure 64.

The interior sensors 30 are positioned to sense the environment within the cavity 63 defined by the enclosure 64 and may include any one or more of an interior water sensor 31, an interior temperature sensor 32, an interior pressure sensor 33, an interior gas sensor 39, and an orientation sensor 41. Multiple temperature sensors 32 may be configured to sense temperature at location(s) within the enclosure of the battery pack 16′, one or more pack internal pressure sensors 33 may be configured to sense pressure at location(s) within the enclosure, one or more water sensors 31 may be configured to sense water ingress into the cavity 63. Alternatively or additionally, the internal sensors may include a humidity sensor configured to sense humidity within the enclosure, such as to detect high humidity levels indicating the presence of water inside the pack. The interior sensors 30 may further include one or more electrolysis gas sensors 39 configured to sense the presence of gas (e.g., hydrogen gas) indicating that electrolysis is occurring. Alternatively or additionally, the interior sensors 30 may include one or more current and/or voltage sensors, and/or an IMM (Isolation Monitoring Module) configured to detect a loss of high voltage isolation from chassis. Alternatively or additionally, the interior sensors 30 (or the exterior sensors 23) may include one or more orientation sensors 41 configured to sense an orientation of the battery, such as to detect that the battery is inverted or otherwise not in an upright position (e.g., indicating that the boat is partially submerged or capsized). In other embodiments, the orientation sensor 41 may be provided on the exterior of the enclosure 64, and/or multiple orientation sensors may be provided to provide reliable orientation information.

Referring primarily to FIGS. 2 and 3 illustrating embodiments of a battery pack 16′, multiple cell modules 18 may be contained within the cavity 63, such as 4-7 cell modules (e.g., 18 a-18 d). For example, each cell module 18 a-18 d may be a 50 V storage unit. The plurality of cell modules (e.g., 18 a-18 d) may be arranged in series to provide the high voltage output. Each cell module 18, or storage section, is comprised of multiple battery cells 19. Each cell module 18 a-18 d may have an associated cell monitoring unit 68 a-68 d configured to monitor parameters of the respective cell module. For example, the cell monitoring unit 68 may be configured to monitor voltage, current, temperature, and/or other parameters of each respective cell module 18. For example, one or more temperature sensors may be positioned on or within each cell module and the produced temperature measurements may be received at the respective cell monitoring unit 68 a-68 d.

Similarly, each cell monitoring unit 68 may be configured to receive input from local current sensors, voltage sensors, pressure sensors, and/or gas sensors configured to sense the local conditions in or around the cell module 18. The cell monitoring units 68 a-68 d may then report the measured temperatures and/or processed temperature data to the battery management system 60, which may be housed with the electronics 79 within the battery enclosure 64 or may be separately housed on or within the battery enclosure 64. Pressure sensor(s) 33 and/or gas sensor(s) 39 may also be located in or around the cell modules 18 and such data may also be received at the cell monitoring units 68, or may be transmitted directly to the battery management system 60.

The BMS 60 is configured to determine a battery state of health and to recognize a hazardous condition based on any one or more of the interior sensor 30 and exterior sensor 23 measurements. For example, the state of health may be determined based on measured temperature and/or rate of internal temperature rise, internal pressure measurements, battery orientation, G-levels endured, water exposure and/or the duration thereof, etc. The BMS 60 and/or a sensor processor module (SPM) 82 may be configured to recognize a hazardous condition of the marine battery based on the sensed values, such as by comparing each or a subset of the sensed values to threshold values or threshold change values. For instance, the SPM 82 may be configured to receive sensor data from the exterior sensors 23 and to detect conditions indicating immersion of the pack and to activate a shock hazard response or other protective response for the battery pack, and also may receive sensor data from the interior sensors 30 to detect thermal runaway and to activate a decommissioning response. The SPM 82 may further be configured to receive information, such as from the cell monitoring units 68, measured by current, voltage, and/or other sensors within the power storage system 16, such as to receive information about the voltage, current, and/or temperature of one more battery cells 19 and/or each cell module 18 within the power storage system 16.

Like the BMS 60, the SPM 82 may be located inside enclosure 64 or on or adjacent to an external surface of the pack. The SPM 82 may be powered by the pack, have its own power source, or be powered by an external power source. The SPM 82 may be incorporated into the BMS or may be a separate and independent control module.

One or more high voltage contactor(s) 69 may be provided that connect the cell modules 18, which are arranged in series, to an output connection attachable to a load on the marine vessel, such as the propulsion system 2. The high voltage contactor(s) 69, or connector(s), may be controllable, such as by the battery management system 60, to disconnect the power storing elements within the pack 16′ from the external connection points on the enclosure 64. For example, one or more high voltage contactor(s) 69 may be placed between the series of cell modules 18 a-18 d and the output terminals 67 a and 67 b on the enclosure 64 configured to connect to the vessel load. When the contactor(s) 69 are opened, the storage elements within the battery are disconnected from the output terminals 67 a and 67 b and thus disconnected from the load and isolated from any contact surface of the enclosure 64.

If abnormal conditions are detected on or within the battery pack 16′ warranting disconnection of the battery from the load, such as the detection of a water exposure event, then the high voltage contactor 69 may be opened to disconnect the high voltage elements inside the pack and prevent conduction to the outside of the pack. In certain embodiments, the pack may be configured such that the high voltage contactor 69 can be reset from outside of the pack. For example, a switch control user interface may be provided on the exterior of the enclosure and configured to allow the high voltage contact 69 to be closed and reset by a user. For example, a rotary switch interface 72 (see FIG. 4) or another type of switch interface may be electrically or mechanically connected to operate the high voltage contactor(s) 69 and manipulatable by the user (or a technician) to reset the contactor(s) 69 once tripped.

Alternatively or additionally, the system may include at least one service disconnect switch 62, which may be a set of switches 62 a-62 c, operable to break the battery down into smaller voltage units. For example, the system may include a plurality of service disconnect switches 62 a-62 c, each positioned between two of the cell modules 18 a-18 d and operable to electrically connect/disconnect the cell modules 18 a-18 d to/from one another in series. Thereby, the service disconnect switch(es) 62 a-62 c are operable to disrupt the series connection and reduce the maximum battery pack internal voltage to touch safe levels (e.g., less than or equal to 60 V DC).

The service disconnect switch(es) 62 a-62 c may be controlled by the BMS 60 (or SPM 82) to enable shock hazard prevention upon detection of a hazardous event, such as a water exposure event. In one example, each service disconnect switch(es) 62 may be a pyrotechnic device that opens the circuit connecting the modules 18 within the battery pack. In one example, the pyrotechnic activator is positioned on an exterior of the enclosure such that heat and gases vented from the pyrotechnic reaction are not vented into the pack. In other embodiments, the disconnect switch(es) 62 a-62 c may be linear switches, slide switches actuated by linear or rotary slides, solenoid driven contactors, relays, or the like. In further examples, each disconnect switch 62 may be a single pole single throw switch, such as configured as a limit switch, that connects or disconnect two cell modules. In other arrangements, the switch(es) 62 may be configured as a multi-position and/or multi-pole switch, such as a rotary switch, or some other type of switch. In some embodiments, the switch(es) 62 may be multi-position configured to place the cell modules 18 in series or parallel, such as to place all of the cell modules 18 a-18 d in parallel for safe discharge during decommissioning as described below.

In certain embodiments, the service disconnect switch 62 may be resettable by a user via a switch control user interface may on the exterior of the enclosure configured to allow the disconnect switch(es) 62 a-62 c to be closed and reset by a user. For example, the rotary switch interface 62′ may be configured to control the disconnect switch(es) 62 a-62 c. In other embodiments, such as in the pyrotechnic embodiment, resetting the service disconnect switch 62 to reconnect the cell modules 18 requires a service technician to replace the service disconnect switch(es) 62 once the disconnection is triggered.

The battery pack 16′ may include a coolant system having coolant lines 71 that run on and around the enclosure 64. Enclosure 64 may include a vent 74, such as a Gortex covered vent, configured to allow the assembly to breathe while preventing water ingress. Current battery certification standards, such as IP69k Certification Standards, require that the pack enclosure, all interconnects, and the venting system does not allow any liquid ingress for a certified time and depth. IP69K certification involves submersion of a battery pack assembly at peak operating temperature to a depth of 2 m for a defined period (typically 2 hours) and vigorous close range power washing of all interconnects with 15000 psi water or steam. However, when a battery pack of normal operating temperature is immersed in liquid (typically water), the pack assembly is cooled, creating a vacuum that will compromise the IP69K waterproof rating. The waterproofing will be compromised more quickly at greater depths, where appreciable pressure is incurred, and thus both pressure and time of exposure are factors that must be considered when monitoring an immersed battery.

In some embodiments, a condensate moisture gathering track may be provided in the bottom of the enclosure that channel moisture to a vent wicking system in normal battery orientation (essentially a vertical straw with a check valve) that forces the liquid out of the pack enclosure each time the assembly heats up to normal operating temperature and pressurizes relative to atmosphere. Additionally, an inert gas cartridge (CO2, N2 or other inert non-toxic, environmentally friendly gas) may be included and configured to pressurize a battery pack enclosure to match or exceed external pressure to prolong the time of exposure to a submersion condition to prevent or prolong the time to water ingress and the associated hazards.

FIG. 3 depicts an exemplary pouch-cell li-ion battery pack 16′ comprising a plurality of modules 18, each containing a plurality of cells 19. The battery enclosure 64 may include a lower housing 64 y that sealably connects to a housing cover 64 x so as to prevent water ingress into the cavity 63. The enclosure may further include an upper housing 65 that sealably connects to the housing cover 64 x, such as to cover the battery electronics 79. A lower trey 66 sealably connects to the lower housing 64 y to form bottom side of the pack enclosure 64 and prevent water ingress on the bottom side. The enclosure 64 may be configured to provide a waterproof seal around the cavity 63 that protects against water ingress when the battery pack is exposed to certain pressures for specified timed durations.

In some embodiments, the BMS 60 and/or SPM 82 may be configured to communicate with the user interface system 35 and/or to control one or more alert devices on the enclosure 64 to provide warnings to a user regarding a water exposure event and/or the status of the automatic shock reduction response. For example, in a situation where the operator inadvertently launches the boat with the drain plug removed, the system may be configured to provide warning to a user of detected water. For example, the system may be configured to open the high voltage contactor(s) 69 and to generate a water exposure alert to advise the user of the water in the hull, such as before opening the disconnect switches 62 a-62 c or performing any automatic response requiring service by a technician to repair, to provide a stepped response to battery pack water immersion.

The SPM 82 and/or BMS 60 may be configured to communicate with or control an alert system 84, which may be integrated with the user interface system 35 of the vessel. The SPM 82 communicates with the alert system 84 via communication link 81, such as a CAN bus. For example, a water exposure alert may be provided on the display 40 of the user interface system 35 advising the user of the unsafe condition and providing an instruction to call for help and/or return home. Alternatively or additionally, an auditory alert may be provided. Alternatively or additionally, an alert may be provided on a remote user interface system, such as on a user's portable computing device that is communicatively connected with the user interface system 35 and/or the alert system 84. For example, the user interface system 35 may incorporate VesselView Mobile™ provided by Mercury Marine and configured to enable battery state of health and/or other battery-related alerts, including a water exposure alert.

Various sensing analysis methods to detect that the battery pack has been exposed to and/or immersed in water are disclosed herein and may be executed by the SPM 82 to detect a water exposure event. If a water exposure event is detected, then one or more electrical connections within the pack may be adjusted to reduce the shock hazard posed by the battery. In certain embodiments, the shock hazard reduction may be performed in stages based on the sensed conditions, so as to avoid unnecessarily disabling the battery system and/or inconveniencing the user more than necessary to sufficiently reduce the hazard.

FIGS. 5-7 depict methods 100 of controlling a marine battery pack exemplifying embodiments of exterior water exposure event detection and response. In FIG. 5, a method 100 of controlling a marine battery pack 16′ includes sensing an exterior of the battery pack 16′ at step 102 via one or more exterior sensors 23. If water exposure is detected at step 104 based on the sensed values, such as based on a sensed exterior temperature, a sensed exterior pressure, and/or a detected presence of water on the exterior of the battery enclosure 64, then a water exposure response is generated at step 106. The water exposure response may include a water exposure alert, such as a visual alert and/or an auditory alert, generated to advise a user that the battery enclosure has been exposed to water. Alternatively or additionally, the water exposure response may include adjusting at least one electrical connection in the marine battery pack 16′ to reduce a shock hazard.

Alternatively or additionally, the water exposure response may include releasing an inert gas inside the enclosure 64 to prevent or prolong the time to water ingress and the associated hazards. For example, an inert gas cartridge (CO2, N2 or other inert non-toxic, environmentally friendly gas) may be contained within the cavity 63 and configured/controllable to pressurize the cavity 63 to match or exceed external pressure to prolong the time of exposure to a submersion condition without water ingress.

FIG. 6 depicts one embodiment of a method 100 of controlling a marine battery pack, wherein the method includes a multi-stage water exposure response based on external conditions sensed over time. As described above, the enclosure may be configured with multiple exterior sensors, including multiple sensor types, positioned around the enclosure 64, such as on the top and bottom of the enclosure. In the example illustrated in FIG. 4, exterior sensor sets 23 a and 23 b are positioned at each of the top side 64 a and bottom side 64 b of the enclosure to sense external parameters at each location. Other placement locations are contemplated and within the scope of the disclosure, such as exterior sensors 23 positioned on the front side 64 c, back side 64 d, and/or lateral sides 64 e and 64 f of the battery enclosure 64. The purpose of multiple external sensor locations is to determine a location and extent of the water exposure, such as whether the battery pack 16′ is partially or totally immersed in water.

Thus, exterior temperature, pressure, and/or presence of water detected at various locations around the pack, may be utilized to determine which portion of the pack is exposed to water and how long that portion has been exposed. For example, a pressure sensor 26 may be configured to detect abnormal external pressure and/or measure the depth of the battery pack 16′ in water, and a time of submersion may be monitored based on the depth. Alternatively or additionally, immersion in water may be detected based on identification of a sharp transition in temperature, such as a threshold temperature change within a short period of time—e.g., over a few seconds—based on measurements from the exterior temperature sensor 25. Similarly, detection of the presence of water on the top or bottom of the battery pack 16′ can indicate whether one or both of the top and bottom of the battery pack 16′ are exposed to water, and thus whether the battery pack is partially or totally immersed.

In the exemplary method illustrated in FIG. 6, water exposure is detected at step 110 based on externally sensed water and/or detection of a threshold temperature change at a first exterior sensor set 23. For example, where water is collecting in the hull of the vessel, where exposure may be detected by an exterior sensor or sensor set 23 b on a lower portion of the battery pack, such as a lower half 91 a of the battery pack. Alternatively, depending on the position of the battery pack relative to the water ingress location, water may first be detected on an upper half 91 b or on one lateral half 92 a, 92 b. Alternatively, depending on the position of the battery pack relative to the water ingress location, water may first be detected on an upper half 91 b or on one lateral half. A water exposure alert is generated at step 112.

As described above, the water exposure alert may include an on-board alert, such as via the user interface system 35 at the helm of the marine vessel. For example, the BMS 60 and/or the SPM 82 may be configured to generate a command to the user interface system 35 to generate a visual alert on the display 40 advising the user that the battery enclosure has been exposed to water. Alternatively or additionally, an alert may be generated to a user and/or owner/manager of the marine vessel, such as via a user's portable computing device configured to enable battery-related alerts.

A high voltage contactor is then opened at step 114 to disconnect the high voltage storage units inside the battery pack 16′ from the output terminals. In certain embodiments, via any one or more of the foregoing alert mechanisms, may be generated to advise the user that the battery has been disabled via opening the high voltage contactor. Alternatively or additionally, one or more alert mechanisms on the battery enclosure 64 may be controlled to generate an alert regarding enabling the high voltage contactor, such as a warning light or an auditory alarm activated to advise someone near the battery and/or with a line of sight to the battery pack 16′ that is no longer connected to the load.

In certain embodiments, the controller, such as the BMS 60 and/or the SPM 82 may be configured to continually monitor the external additions of the battery pack 16′ and to take further steps to reduce the shock hazard should further water exposure events be detected. For example, the controller may be configured to continue assessing whether water is detected, and thus whether the threat of water ingress is continued. At step 116, steps are executed to determine whether water continues to be detected for a threshold period of time. If so, then one or more disconnect switches 62 a-62 c are opened at step 140 to break the battery down into smaller voltage units, such as by disconnecting the plurality of cell modules 18 from one another such that they are no longer electrically connected together in series. Thereby, the total voltage level within the pack 16′ is significantly reduced. The threshold period of time may be based, for example, on the waterproof rating of the pack, such as less than or equal to a rated time underwater. FIG. 7 illustrates one such example.

The controller may further be configured to detect partial or total immersion of the battery pack 16′, represented at step 118. For example, sensor data from multiple sensors positioned on different exterior surfaces of enclosure 64 may be assessed to determine where water is (and is not) present. For example, if water is only detected on a lower half 91 a of the enclosure 64 for a period of time, then partial immersion may be determined. If water is detected on a lower half 91 a and is also detected on an upper half 91 b of the enclosure 64, such as detected by the external sensor set 23 a positioned on a top side of the enclosure 64, then total immersion may be identified. In various embodiments, the system may be configured to open the disconnect switches upon detection of partial immersion, or may require total immersion, or partial/total immersion for a period of time, before opening the disconnect switches at step 140.

Once the disconnect switches are opened, a disconnect alert may be generated at step 142, such as via the alert mechanisms described above. The disconnect alert is configured to advise the user that the battery has been broken down into smaller voltage units, and thus the full battery voltage is no longer available. In certain embodiments, the opened disconnect switches 62 a-62 c may be resettable by a user. In other embodiments, such as where the disconnect switch(es) are pyrotechnic devices, opening the disconnect switches may require service by a trained technician to reconnect or replace the switch(es) 62 a-62 c and reestablish the battery voltage. Accordingly, the disconnect alert may be configured to advise the user on steps necessitated based on the shock hazard reduction action that has been performed, including in view of opening the disconnect switches and/or opening the high voltage contactors.

FIG. 7 depicts another embodiment of method 100 for controlling a marine battery pack 16′ according to the present disclosure. A water exposure event is detected outside the battery pack using one or more exterior sensors at step 111. A water exposure alert is then generated at step 112 and one or more high voltage contactors are opened at step 114, such as described with respect to FIG. 6. Steps are then executed to determine whether the marine battery is at least partially immersed based on one or more exterior pressure measurements. If the external pressure measured by the exterior pressure sensor exceeds a calibrated threshold or a threshold pressure increase in a predefined time period at step 120, then the controller determines that at least partial immersion is detected and a timer is started at step 122.

The exterior pressure is continually determined at step 124 based on pressure data from one or more exterior pressure sensors 26 on the enclosure 64. The pressure measurements are compared to a maximum pressure at step 126, which may be a maximum rated pressure that the enclosure 64 is configured to withstand for any period of time. If the maximum pressure is exceeded at step 126, which would indicate that the battery pack 16′ is relatively deep underwater, then the disconnect switches are opened at step 140. Based on the measured external pressure, a calibrated time period is identified and monitored to determine whether battery pack 16′ has been exposed to a given pressure for the maximum rated time period at that pressure. As the external pressure increases, the time threshold decreases. If the calibrated threshold time based on the measured external pressure is reached at step 128, then the disconnect switches are opened at step 140.

In other embodiments, different steps may be executed to detect and monitor partial or total immersion, which may be in addition to the foregoing pressure-based analysis or in lieu of the pressure-based analysis. For example, water detection, temperature measurements, orientation monitoring, G-force measurements, and/or other parameters may be utilized as described herein to detect the presence of water and/or to identify partial or total immersion.

After the service disconnect switch(es) 62 are opened, the battery pack will have several low voltage modules that still contain substantial amounts of stored electrical energy. Other steps may be taken to mitigate shock and/or thermal conditions, such as de-energizing the battery cells via balancing resistors in the battery management system (BMS) and/or draining current from the battery cells by other means. Stored electrical energy in the batteries may be dissipated more quickly with high capacity liquid-cooled ballast resistors or with touch-safe voltage electrical loads powered by the cell modules 18 (e.g., in parallel). For example, one or more cooling mechanisms may be powered by the cell modules 18 to both drain the stored energy and cool the cavity 63. In one embodiment, the cooling activity of the battery cooling system may also be increased by maximizing the water pumping around the battery enclosure to maximize cooling the battery back as much as possible without completely decommissioning and destroying the power storage system.

Finally, if the mitigation efforts are unsuccessful and the battery hazard increases further, such as detection of thermal runaway, a battery fire igniting or meeting threshold conditions indicating that a battery fire is imminent, then steps may be executed to automatically decommission the power storage system, such as flooding it with water, injecting foam, and/or injecting inert gas into the enclosure of the battery pack. While such decommissioning steps likely permanently destroy the power storage system and the elements therein, the decommissioning steps are devised to reduce the hazard posed to passengers aboard a marine vessel and/or to the surrounding environment of the power storage system.

A battery pack ingress protection rating is for a specified depth and time. As described above, enclosure 64 is configured to provide a waterproof seal around cavity 63 that protects against water ingress when the battery pack is exposed to certain pressures for specified time durations. However, after a certain period of exposure underwater, or due to a malfunction of the enclosure, water ingress is possible which can lead to thermal runaway and unsafe battery conditions. Extended submersion of a battery pack in water will eventually lead to water ingress, cell shorting, uncontrolled discharge, and a battery pack thermal event. Assuming that the shock reduction steps described above have been executed, including disabling the battery contactors and tripping the service disconnect switch, automated decommissioning of the battery may be performed. While the battery pack 16′ does include a cooling system having coolant lines 71 that run on and around the enclosure 64, the cooling system is insufficient for cooling the battery in the event of significant water ingress and/or a thermal runaway event.

Where a hazardous battery event is imminent or is occurring, the marine battery pack may be configured to automatically decommission itself to maximize safety. The inventors have recognized that the system can utilize the operational environment of a marine application as a source for battery cooling to remove heat and gas buildup during a thermal event. Thus, in one embodiment, the system uses the body of water the vessel is floating on to provide cooling water that can be pumped up through the pack, inside the enclosure to cool the cells and flush out cell vented gases. Such a water-flooding system may be utilized for decommissioning marine batteries on marine vessels experiencing a catastrophic event where the battery poses a safety risk, and also may be used on any li-ion storage system with direct access to a body of water, such as power storage and/or charging systems on a dock or in a marina.

One step in the process for battery decommissioning may include pumping water through the battery enclosure, including around the cell modules 18 and battery cells 19 to remove heat therefrom as well as to remove electrolysis gases that may be generated. Referring again to FIGS. 3-4, an electric pump 76 may be configured and controllable to pump water through a water inlet 78 in enclosure 64. The water is forced up through the enclosure and exits through outlet 80. A continual flow of water is thereby provided to cool the battery cells 19 until the energy stored therein is sufficiently dissipated that heat and gas generation is no longer a problem.

In various embodiments, the pump 76 may be located inside the enclosure 64, such as configured to draw water into the inlet 78 from inside, or may be connected to the outside of the enclosure 64 or other housing on the battery pack 16′ and configured to force the water through the pack from inlet to outlet. Activation of the pump 76 (and/or the access port) may be controlled by the BMS 60 and/or SPM 82 configured to receive data gathered by sensors and sensing systems on and in the battery pack 16′, particularly the internal sensors 30, and to determine when decommissioning is warranted—i.e., when an event warranting decommissioning is detected.

The electrically driven water pump 76 is powered by a battery power source, which could be an external power supply associated with and/or housed with the pump (inside or outside the enclosure 64) or could be from the battery pack itself. In one embodiment, the remaining stored energy in the battery pack can be used as a source of power for pumping water through the enclosure. For example, the pump 76 may be configured to draw power from one or more of the cell modules 18, which has the added benefit of dissipating energy from the battery cells 19 and expediting the process of getting the battery pack 16′ to a safe and stable state.

This embodiment will be effective for any li-ion battery assembly that has access to a water source. It would also work for vehicle fires if the emergency response personnel had a water connection port on the battery pack to provide a water source to the pump 76. This reduces the time required to get cooling to cells that have reached thermal event temperature and would flush out electrolysis gas.

The modules can be used in parallel to power an electric water pump configured to pump water through the pack to cool the cells and flush gasses out. For example, the system may be configured to operate pump 76 until the power source, be it the cell modules 18 or an external power supply, is depleted. The pumping rate will naturally taper off as the stored battery energy is fully dissipated fully decommissioning the battery pack and mitigating the hazards. Thereby, the hazard is reduced in two ways: 1) by using the surrounding water to reduce the temperature and gas buildup, and 2) by draining the stored energy in the batteries to drive the pump until a low state of charge (SoC) is reached.

In another embodiment, the battery pack 16′ may be provided with an electronically controlled access port that is controllable to allow water to enter or exit the pack either naturally or by a controlled means when decommissioning is warranted.

In certain embodiments, the response to a detected battery event warranting decommissioning may further include releasing or injecting a liquid foam into the battery pack to coat and insulate the exposed conductive surfaces inside the battery pack enclosure to prevent shorting of the cells if water enters the battery pack. This foam will have strong surface wetting properties to coat and insulate the exposed conductors and prevent water electrolysis. The foam may be designed to remain in a liquid state to allow for water pumping through the pack to cool the cells following the foam injection step.

Alternatively or additionally, the battery decommissioning system may be configured to disperse a refrigerated foam with a dielectric refrigerant, or chemical agent to create an endothermic chemical reaction that converts a liquid to an inert gas to refrigerate the foam. The system may be configured to fill the enclosure with such a heat dissipating material to generate small closed-cell bubbles to fill the pack, coat the exposed internal contacts with an electrically insulating layer, provide rapid cooling of the battery cells, and potentially stop the thermal event based on the localized cooling of the cells experiencing a thermal event. To provide just one example, sodium bicarbonate and citric acid may be used to create small closed-cell bubbles in the battery enclosure. The resultant endothermic (heat absorbing) chemical reaction and liquid to gas phase change combine to instantly cool the battery cells by hundreds of degrees centigrade.

In one embodiment the foam may be a hardening foam that fills the enclosure and coats the contacts. In another embodiment, the system may be configured to use a foam that remains liquid such that, upon detection of continued thermal propagation, the injected foam or other heat dissipating material may be followed by pumping water up through the battery pack. The pumped water will flush out the foam, along with gas and heat buildup, and may be performed until the pack is fully cooled and/or the stored electrical energy is mostly or fully dissipated.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. Certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art in view of the present disclosure. Such other examples are intended to be within the scope of the claims if they have features or structural elements that do not differ from the literal language of the claims, or if they include equivalent features or structural elements with insubstantial differences from the literal languages of the claims. 

We claim:
 1. A marine battery pack comprising: a battery enclosure having an exterior and an interior defining a cavity, wherein the battery enclosure is configured to protect against water ingress into the cavity; a plurality of cell modules within the cavity, each comprising a plurality of battery cells; at least one exterior sensor on the battery enclosure configured to sense at least one of an exterior temperature, an exterior pressure, and a presence of water on the exterior of the battery enclosure; a controller configured to: identify a water exposure event based on the at least one of the exterior temperature, the exterior pressure, and the presence of water on the exterior of the battery enclosure; and generate a water exposure response.
 2. The marine battery pack of claim 1, wherein generation of the water exposure response includes generating a water exposure alert.
 3. The marine battery pack of claim 2, wherein the controller is configured to generate the water exposure alert by sending a command to a user interface system to generate a visual alert advising that the battery enclosure has been exposed to water.
 4. The marine battery pack of claim 1, wherein generation of the water exposure response includes adjusting at least one electrical connection in the marine battery pack to reduce a shock hazard.
 5. The marine battery pack of claim 4, wherein adjusting at least one electrical connection includes at least one of operating a high voltage contactor to disconnect the plurality of cell modules from an output terminal of the battery pack and operating at least one disconnect switch to disconnect the plurality of cell modules from one another to reduce voltage levels within the battery pack.
 6. The marine battery pack of claim 1, further comprising a high voltage contactor inside the battery enclosure configured to control connection of the plurality of cell modules to an output terminal of the battery pack; wherein the water exposure response by the controller includes controlling the high voltage contactor to disconnect the plurality of cell modules from the output terminal of the battery pack.
 7. The marine battery pack of claim 1, further comprising at least one disconnect switch configured to control connection of the plurality of cell modules together in series; wherein the water exposure response by the controller includes controlling the at least one disconnect switch to disconnect at least a portion of the plurality of cell modules from one another to reduce voltage levels within the battery pack.
 8. The marine battery pack of claim 1, wherein the at least one exterior sensor includes a water sensor; wherein the controller is configured to identify the water exposure event when the exterior water sensor senses the presence of water.
 9. The marine battery pack of claim 1, wherein the at least one exterior sensor includes a pressure sensor configured to sense the pressure outside of the battery enclosure; wherein the controller is configured to identify the water exposure event based on detection of at least one of a threshold pressure increase and a threshold pressure outside the battery enclosure.
 10. The marine battery pack of claim 1, wherein the at least one exterior sensor includes a temperature sensor configured to sense the exterior temperature; wherein the controller is configured to identify the water exposure event based on detection of at least a threshold change in temperature outside the battery enclosure.
 11. The marine battery pack of claim 1, further comprising an inert gas cartridge configured to release inert gas into the cavity, wherein generation of the water exposure response includes releasing the inert gas into the cavity to increase pressure in the cavity to prevent water ingress.
 12. A method of controlling a marine battery pack, the method comprising: sensing, via at least one exterior sensor on a battery enclosure of the battery pack, at least one of an exterior temperature, an exterior pressure, and a presence of water on the exterior of the battery enclosure; detecting a water exposure event, with a controller, based on the at least one of the exterior temperature, the exterior pressure, and the presence of water; and generating, with the controller, a water exposure response.
 13. The method of claim 12, wherein generating the water exposure response includes controlling a user interface system to generate a water exposure alert.
 14. The method of claim 12, wherein generating the water exposure response includes adjusting at least one electrical connection in the marine battery pack to reduce a shock hazard.
 15. The method of claim 14, wherein adjusting at least one electrical connection includes operating at least one of a high voltage contactor to disconnect a plurality of cell modules in the battery pack from an output terminal of the battery pack and at least one disconnect switch to disconnect the plurality of cell modules from one another to reduce voltage levels within the battery pack.
 16. The method of claim 12, wherein the at least one exterior sensor includes at least one water sensor, and wherein detecting the water exposure event includes detecting the presence of water with the at least one water sensor.
 17. The method of claim 16, wherein detecting the water exposure event includes sensing the presence of water with the at least one water sensor for a predetermined time prior to generating the water exposure response.
 18. The method of claim 12, wherein the at least one exterior sensor includes a pressure sensor configured to sense the pressure outside of the battery enclosure, and wherein detecting the water exposure event includes detecting at least one of a threshold pressure increase and a threshold pressure outside the battery enclosure.
 19. The method of claim 12, wherein the at least one exterior sensor includes a temperature sensor configured to sense the exterior temperature outside of the battery enclosure, and wherein detecting the water exposure event includes detecting at least a threshold temperature change outside the battery enclosure.
 20. The method of claim 12, wherein generating the water exposure response includes releasing the inert gas into the cavity to increase pressure in the cavity to prevent water ingress.
 21. A method of controlling a marine battery pack, the method comprising: sensing, via at least one exterior sensor on a battery enclosure of the battery pack, at least one of an exterior temperature, an exterior pressure, a presence of water on the exterior of the battery enclosure, and a battery orientation; detecting a water exposure event based on the at least one of the exterior temperature, the exterior pressure, the presence of water, and the battery orientation; and automatically controlling with a controller at least one electrical connection in the marine battery pack to reduce a shock hazard posed by the battery.
 22. The method of claim 21, wherein controlling the at least one electrical connection includes controlling a high voltage contactor with the controller to disconnect a plurality of cell modules in the battery pack from an output terminal of the battery pack.
 23. The method of claim 21, wherein controlling the at least one electrical connection includes controlling at least one disconnect switch with the controller to disconnect a plurality of cell modules in the battery pack from one another to reduce voltage levels within the battery pack.
 24. The method of claim 21, wherein the at least one exterior sensor includes at least one water sensor, and wherein detecting the water exposure event includes sensing the presence of water on the exterior of the battery enclosure.
 25. The method of claim 24, wherein detecting the hazard includes sensing the presence of water with the at least one water sensor for a predetermined time prior to adjusting the at least one electrical connection.
 26. The method of claim 21, wherein the at least one exterior sensor includes at least one of a pressure sensor and a temperature sensor, and wherein detecting the hazard includes detecting a threshold change in pressure or a threshold temperature outside the enclosure indicating at least partial immersion of the battery in water.
 27. The method of claim 21, wherein the at least one exterior sensor includes an orientation sensor, and wherein detecting the hazard includes detecting at least a threshold change in orientation of the battery pack. 